The HTTP 101 Switching Protocols response code indicates the protocol the server is switching to as requested by a client which sent the message including the Upgrade request header.
The server includes in this response an Upgrade response header to indicate the protocol it switched to. The process is described in detail in the article Protocol upgrade mechanism.
101 Switching Protocols
Switching protocols might be used with WebSockets.
HTTP/1.1 101 Switching Protocols Upgrade: websocket Connection: Upgrade
| Specification | Title |
|---|---|
| RFC 7231, section 6.2.2: 101 Switching Protocol | Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content |
Upgrade426 Upgrade Required
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https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/101